Such electromagnetic valves are needed for various purposes in internal combustion engines. An example of such a valve is an electromagnetically actuated recirculation air valve for the recirculation of compressed fresh gas, possibly with recirculated exhaust gas, from the pressure side of a compressor of a turbocharger back to the suction side of the compressor. The connection between the pressure side and the suction side of the compressor obtained by a bypass line is required for the transition from a high load to the propulsion operation of the internal combustion engine to prevent a high delivery by the turbocharger pump against a closed throttle valve, to prevent the resulting pumping effect, and to prevent an excessively sudden drop of the turbo speed with resulting thermodynamic problems.
The valve seat is typically formed in the bypass line which is mounted to the turbocharger housing. The control element is therefore passed onto the valve seat through the corresponding opening in the bypass line, after which the actuator is screwed to the housing of the bypass channel. Care must be taken with these valves, however, that the unit formed by the armature and the control element does not first drop out of the actuator. This makes assembly and transport significantly more difficult. It is therefore desirable for the valve to be inserted into the flow housing in a completely pre-assembled state and be there fastened.
An electromagnetic valve is described in DE 197 49 641 A1 where, for transportation purposes, an additional protective cap is slipped over the control element formed by sleeves and sealing rings. The additional protective cap must be removed prior to assembly so that, during assembly, care must still be taken so that the components of the control unit remain correctly positioned with respect to each other.
A recirculation air valve is described in DE 10 2004 044 439 B4 where an outward directed seal is arranged on the control element. The outward directed seal rests on a housing part so that the control element with the armature cannot slide out of the housing. The seal is, however, thereby subjected to mechanical stress which may result in damage to the sealing ring and leakages during operation.
A similar problem also exists with a recirculation air valve as described in EP 1 941 138 B1. The closing body is here provided with an annular enlargement in the region directed to the actuator where the annular enlargement, prior to the assembly of the valve, rests against a sealing ring of a V-shaped cross section. The unit formed by the armature and the control element in this embodiment is also prevented from dropping out by the seal, which could thereby be damaged.